It's a bought and paid for "title" that people use to boost their egos. Yea, they have a process (not a difficult one) but in the end it's nothing more than a fancy title for resume enhancement.
I hadn't looked in a while, so I went and looked up the requirements because as I remembered it was not trivial. Here they are:
* 2+ years as a CFI and 1000+ hours of dual given
* 16+ points from the "Instructor" category, which can be:
- 4 points for each checkride endorsement given
- 2-4 points for teaching a college aviation class
- 1-3 points for teaching a ground school
- 1 point for every 5 insurance checkouts/aircraft transitions given
- 1 point for every 5 flight reviews given
- 1 point for every 5 endorsements given (hi perf, complex, tailwheel, hi alt)
- If you're a DPE, 1 point for every 5 checkrides given
* 4+ points from the "Educator" category: (Developing educational materials)
- 3 points for aviation vocational classes
- 1-3 points for high school aviation classes, original ground school courses, curricula
- 1-2 points for FIRCs, industry courses, multimedia, or aviation apps
- 1 point for safety seminars, guidebooks, manuals, published magazine/journal articles, and that sort of thing
* 2+ points from "Service to the Aviation Community" category:
- 1-5 points as an airport manager
- 1-3 points for an aviation related website
- 1 point each for CAP, Scouts, Young Eagles, Angel Flight or other service org leadership
- 1 point each for FAASTeam rep, ASN rep, EAA technical counselor, grant proposal, or FAA NPRM response
* 2+ points from the "Professional Activity" category, focused on the instructor learning more:
- 1-4 points for building a homebuilt aircraft
- 3 points for becoming a DPE
- 1-3 points for obtaining an additional certificate or rating, or attending an aviation college class
- 1-2 points for aviation conferences/conventions
- 1 point each for aircraft/avionics transitions, ground school for cert/rating, CSIP, Wings program, FIRC, BFR/IPC, etc
- 1 point for owning or restoration of a certified aircraft
- 1 point for every 5 safety seminars attended
* At least 32 total points - And no duplication is allowed across the categories.
So yeah, not at all "buying a title".

Master CFI is the real deal, it's Gold Seal that's relatively easy.